The five operational beamlines that constitute the Surfaces and Interfaces village include the Angle Resolved Photoelectron Spectroscopy (ARPES) beamline (I05), the Nanoscience beamline (I06), the Surface and Interface Diffraction beamline (I07), the Surface and Interface Structural Analysis beamline (I09) and the Beamline for Advanced Dichroism Experiments (I10). In addition, the Versatile Soft X-ray Scattering (VERSOX) beamline (B07) is in its final stages of construction, before user commissioning. The facilities within the village offer a comprehensive range of techniques to our users, enabling them to determine the physical and electronic structure of their samples using diffraction and spectroscopic techniques. New capabilities have been added over the last year including Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS), Near Edge X-ray Absorption Fine Structure (NEXAFS), Hard X-ray Photoelectron Spectroscopy (HAXPES) and spatially resolved Nano-ARPES. The offline capabilities have also been updated, the chemistry laboratory in particular has been expanded to become a village wide facility with more bench space, a second fume cupboard and facilities for ellipsometry and Brewster angle microscopy, tensiometer measurements and differential scanning calorimetry.
The science directions covered by the village have continued to expand; for example we have welcomed users with interests as diverse as magnetic materials with potential for high density storage, biologists studying how proteins interact with lipids in the cell membrane, novel materials containing magnetic structures called skyrmions, the development of photovoltaic device structures during vacuum deposition and catalytic materials studied in situ to link the structure to their efficiency. Other groups have exploited the coherent properties of the synchrotron beam to study structures using soft X-ray holography or coherent X-ray diffraction with hard X-rays. This year’s science highlights comprise investigations of some complex behaviour in samples including iron based superconductors, where the influence of how the spin orbit coupling affects the detailed electronic structure has been reported, based on ARPES experiments on I05. Two of the reports focus on magnetic effects that have potential importance for memory technology, including the development of multidomain skyrmion lattices on I10 and the potential of antiferromagnetic materials for fast switching of the magnetic state, studied at I06. Meanwhile the catalytic activity of iron oxide films on silver surfaces has been investigated through careful determination of the monolayer structure at I07. Many of the investigations continue to probe fundamental properties of materials, such as the I09 study showing the development of the Mott insulator transition in VO2 highlighting how strain in the material can lead to a Mott transition in specific electron orbitals but not others.
Figure 1: The UHV sample station on I07.
Specific technical developments have been ongoing across the village. On I05, the high resolution branch has continued to deliver data of exceptional quality on a wide variety of cleaved samples including superconductors and two dimensional materials. High quality data from samples grown in the attached molecular beam epitaxy (MBE) system has been achieved for the first time on thin film gadolinium doped EuO structures. The Nano-ARPES branch has undergone extensive optimisation with users and has now entered regular operation attracting many experienced and new researchers.
Figure 2: A visit by the Vice-Chancellor of Oxford University, Louise Richardson and Director of Estates to I06 in January 2017.
I06 is undergoing an upgrade to its branchline to enable faster changeover between experiments. It will result in the time resolved scattering chamber and the superconducting magnet being permanently installed and there will be the possibility of mounting user chambers at the end of the line.
Figure 3: Principal Beamline Scientist, Georg Held with Rosa Arrigo, Federica Venturini and David Grinter in the B07 experimental hutch.
Over the last year I07 has focused on improving the sample environments available to users. These include MINERVA, a vacuum deposition system for monitoring the developing hard X-ray scattering signal during growth of organic molecules, particularly of relevance to new photovoltaic materials. Additionally, a vacuum baby chamber has been developed to enable transfer of ultrahigh vacuum prepared samples with subsequent X-ray diffraction measurements during in situ electrochemistry and photochemistry experiments. The double crystal detector is performing particularly well to study liquid surfaces after the replacement of the positioning stages significantly improved the reliability and repeatability.
I09 is developing a new end station for its high energy branch that will be optimised for HAXPES. The upgrade will result in a 10 μm sized beam, ideal for small samples, and includes a chamber, multi-axis sample manipulator and SPECS Phoibos 225 analyser that will enable more flexibility in the modes of operation.
BLADE (I10) has developed an electromagnet for X-ray dichroism experiments capable of fields up to 2 T and with very good control for low fields. This complements the existing high field magnet (14 T) to provide improved data for a wider range of different sample types. New area detectors on the soft X-ray scattering end station (RASOR) have enabled significant improvements in the data quality.
The team at B07 is optimising its first branch, which focuses on near ambient pressure (NAP) measurements, but continues to develop the instrumentation for the second line that will operate simultaneously. This will be developed into a high throughput facility for XPS and NEXAFS, in a number of different environments. When complete, B07 will enable studies of heterogeneous catalysts, pharmaceuticals and biomaterials under realistic conditions, environmental and space science studies on liquids and ices, heritage conservation, and the study of electronic and photonic materials.
The Surfaces and Interfaces village is continually developing its range of techniques and measurement facilities in consultation with the users. Please get in touch if you would like to discuss any future developments on the beamlines or in the off-line facilities. If you have any questions regarding possible measurements at Diamond or would like advice on how we may help with your science programme then please contact us. We look forward to welcoming you to the Surface and Interface village beamlines at Diamond.
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
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